Is there any way to add a close button (or any button) through the IPC mechanism? I know you can do something like $Mod+x to close a window, but I'd honestly rather just use a button. Maybe the button can have a tooltip reminding you what close is set to
I have a feeling the i3 maintainers won't want to add a close button, however.
When you full screen some windows that have window decorators turned on (like browsers) then they show the minimise, close, maximise buttons. However, I always try to use the built in hot keys for closing a program rather than unceremoniously killing them with the close client hotkey.
I have a feeling the i3 maintainers won't want to add a close button, however.